1. Field of Invention
This invention relates to battery jumper cables designed to alert the user as to whether storage batteries are connected in proper parallel relationship for charging the weaker battery or for starting a motor vehicle containing the weaker battery. Also this invention relates to battery jumper cables designed to permit the flow of charging current between the two storage batteries only when the batteries are connected in proper parallel relationship for the charging or starting functions outlined above.
2. Description of Prior Art
The improper connection of two storage batteries for charging purposes or for starting an automobile has long posed problems of safety. Connecting storage batteries, other than in parallel, can cause damage to the batteries and associated alternators and can even cause fires if arcing ignites the gases given off by the batteries. Prior art has sought to alleviate the problem by various types of polarity indicators to indicate when battery jumper cables are properly connected. An alternative approach has been circuitry designed to prevent the flow of charging current unless the batteries are connected properly. Various types of diodes and bulbs have been used as indicator lights in the first approach. Various types of power transistors and electromagnetic switches have been used in the alternate approach. Silicon diodes were found to be sensitive to overloads and rectifiers were found to be vulnerable to high currents of reverse polarity. These polarity control systems were adapted both for use with battery charging rectifiers and with independent battery jumper cables.
In the protective circuitry prior art, manual steps were usually involved. Power transistors or other one way electrical devices were used to block current during an improper hookup. After a proper hookup, manual switches were used to energize electromagnetic switches to complete the continuity of charging current between the batteries. None of the systems of the prior art appear to be fully automatic as is the present invention. Also, none of the cables in the prior art provide a disconnect means for opening the circuit by push button for sparkless disconnection of the two batteries.
Prior art known to this inventor includes the following U.S. patent numbers:
______________________________________ 3,259,754 7/1966 Matheson 3,281,816 10/1966 Raymond 3,308,365 3/1967 St. John 3,413,487 11/1968 B. J. Gershen 3,778,801 12/1973 Nudelmont 3,906,342 9/1975 Pfouts 4,063,171 12/1977 Schweitzer, Jr. 4,145,648 3/1979 Zender 4,180,746 12/1979 Giuffra 4,238,722 12/1980 Ford ______________________________________